United grounds 737 Max 8 planes through early July

April 16 (UPI) -- United Airlines grounded all Boeing 737 Max 8 flights through early July, joining American and Southwest airlines.

United officials said they will continue using spare aircraft and other solutions to fill in the gaps in its flight schedule while the Max 8 fleet is grounded. 

The Max 8 aircraft were grounded by the Federal Aviation Administration last month an  Ethiopian Airlines crash, months after another one involving Lion Air in Indonesia. The crashes killed a combined 346 people.

Boeing has been working with airlines to test a software fix to fix the planes' automatic anti-stalling system, which could be to blame for the crashes. But United and other airlines are not planning to resume flying the planes very soon.

In its fourth quarter earnings reported Monday, United's revenues came in at the high end of its full-year adjusted diluted earnings per share target. The airline had a net income of $2.1 billion, or $7.70 diluted earnings per share.

"United's financial performance is a testament to the successful implementation of the first year of our strategic plan and to the record-setting operational performance powered by the more than 90,000 airline professionals who work at United," United CEO Oscar Munoz said.

United took delivery of 10 new Boeing 737 Max 9 aircraft and placed an order for 24 new 737 Max aircraft in December.